A capsule filter cigarette is widely known, in which a capsule is situated in a cavity formed in a cigarette filter. The cavity is formed, for example, between filter segments created by dividing the filter. This capsule filter cigarette is designed so that a flavoring agent or adsorbent enclosed in the capsule works when the capsule is broken at the time of smoking. If the flavoring agent or adsorbent is liquid, after the capsule is broken with fingers, the content liquid of the capsule permeates the tipping paper covering the cigarette filter. This causes the problem that the content liquid adheres to the fingers holding the tipping paper. Another problem is that, if the content liquid permeates as far as the wrapping paper that covers shred tobacco, cigarette flammability is degraded. Furthermore, if the content liquid that has permeated the wrapping paper is inflamed, this affects the taste and flavor of the cigarette.
The cigarette filter is made by the steps of wrapping filter fiber in rolling paper and thus producing a filter segment, and wrapping the filter segment in shaping paper (wrapping the whole of each filter segment if there are plural filter segments or wrapping all filter segments and capsules together if capsules are arranged in cavities between the filter segments). If the shaping paper is made of permeation-preventing material such as oil-proof material, it is possible to prevent the event in which the content liquid permeates the tipping paper. Instead, however, there will be another problem that the content liquid permeates the rolling paper located on the inner side of the shaping paper and continues to permeate as far as the wrapping paper.
The inventors of the present invention carried out a review of the foregoing problem and replaced the rolling paper with the one made of permeation-preventing material such as oil-proof paper. In the result, it was newly found that the content liquid flowed through a gap between the rolling paper and the shaping paper, and between the rolling paper and filter fiber, and permeated the wrapping paper. Upon further review, the inventors utilized, as a filter segment, NWA (Non Wrapped Acetate) without rolling paper. Again, the content liquid flowed through the gap between the NWA filter fiber and the shaping paper and ended up permeating the wrapping paper. The inventors thus recognized that the above-mentioned way was inadequate for solving the problem.
In respect of the same problem, Patent Document 1 discloses a cigarette filter in which a capsule containing fluid material is placed in an area sandwiched between filter segments. This cigarette filter has an outer cover made of material that is virtually impervious to the fluid material enclosed in the capsule, and thus covers the capsule in this outer cover. In short, impervious material (cellophane, polyvinylidene chloride or virtually impervious film or sheet) is used to prevent the permeation of the content liquid enclosed in the capsule. However, if the impervious material mentioned in Patent Document 1 is used, there is the possibility to adversely affect the wrapping of filter fiber and the capsule. Since it is assumed that the impervious material mentioned in Patent Document 1 is not air-permeable, the material is not capable of taking in air for attenuation into the cigarette filter. This can cause a disadvantage in light of the product design of the cigarette. One way to take in air for attenuation into the cigarette filter is to use laser perforation. Considering factory health and safety, however, it is not preferable to use laser, for example, to perforate cellophane.
There is another well-known capsule filter cigarette, in which a capsule is embedded in filter fiber instead of being inserted in a cavity so that the content liquid of the capsule is adsorbed by the filter fiber. This cigarette makes it a little difficult to squash the capsule with fingers together with the filter fiber. It is also difficult to embed the capsule in a certain place of the filter fiber.